Money managers added to their net-long positions in silver for the fourth time in five weeks, chasing the kind of returns that in the first three months of the year sent the precious metal to its biggest quarterly gain since 2012. The price surge is showing signs of fatigue, with futures posting two consecutive weekly declines and an almost 4 percent drop for May.

Silver leapfrogged gold in mid-April as the best-performing precious metal as data signaled a resilient U.S. expansion and a stabilizing Chinese economy. The commodity entered a bull market a few days later. Optimism on the outlook for industrial demand has since wavered, as some factory gauges released this month fell short of expectations.

“The intensity of bullishness that has come into this space in the last four months has just been mind-blowing,” Shree Kargutkar, an associate portfolio manager at Sprott Asset Management, which oversees C$9 billion ($7 billion), said in a telephone interview May 11. “Silver’s done very impressively this year.”

Money managers increased their net-long holdings in silver by 7 percent to 71,656 U.S. futures and options contracts in the week ended May 10, according to Commodity Futures Trading Commission data released three days later. On Monday, silver futures for July delivery rose 0.1 percent to close at $17.154 an ounce at 1:44 p.m. on the Comex in New York, after falling 2.3 percent last week. Prices are up 24 percent this year.

Silver and other precious metals have benefited from mounting speculation that risks to global growth will restrain the Federal Reserve’s pace of interest-rate increases. Lower borrowing costs are a boon to silver and gold because the metals don’t offer yields or dividends. Silver, which also has more industrial uses, gained an added boost from reports last month showing improvement in Chinese and U.S. manufacturing.

Output from mines will fall 2.4 percent to 784.8 million ounces in 2016 from a year earlier, according to New York-based researcher CPM Group. That will be the first decline since 2011. Fabrication demand including jewelry, electronics and solar panels will rise, while secondary supply, including scrap and melted coins, will drop, CPM said.

Bank of America Merrill Lynch raised its price forecast by 8 percent to $16.47 for 2016. In a report April 25, the Charlotte, North Carolina-based bank cited the end of a supply glut, saying that “fundamentals are now the strongest in years.”

With data this month showing signs that manufacturing growth is in danger of stalling, some investors are reassessing the outlook. A report Saturday showed industrial production in China slowed more than economists forecast in April.

Standard Chartered Plc flagged the risk of the silver rally fading in its report on April 28, before the metal posted the biggest monthly gain since 2013. The jump in prices in the first four months of the year has “not been supported by a shift in fundamentals,” the bank said. In a separate report on May 9, Standard Chartered said there is an “absence of industrial demand support” for prices.

“We went from no one wants to own these things to everybody wants to own these things now,” said John LaForge, the Sarasota, Florida-based head of real assets at Wells Fargo Investment Institute, which oversees $1.6 trillion. “We’ll get to a point here pretty soon, and maybe this is it, where the investor just gets tired of it and doesn’t really have any great fundamental backing behind why they should own silver” at current prices, he said.